Photograph (above): Dimitrios Kambouris/Getty Images for Samsung
Kinney, 33, popped the question to Gaga on Valentine's Day, reported Us magazine.
Gaga, 28, confirmed the engagement herself via Instagram, sharing a picture (below) of her huge, heart-shaped diamond ring. "He gave me his heart on Valentine's Day, and I said yes!" she captioned the photo.
The singer stepped out yesterday and grinned from ear to ear but did not flash her new engagement ring initially.
Wearing a purple fur coat, the songstress strategically covered her ring finger with her hand and under her coat.
The couple apparently celebrated at Gaga's family's restaurant, Joanne Trattoria, on the Upper West Side of Manhattan, after Kinney proposed her.
The singer and her fiance first met on the 2011 set of Gaga's You & I music video, which was shot in Nebraska.
Gaga wore her mother's actual wedding gown in scenes of the video, which starred Chicago Fire hunk Kinney as the object of her affection. They started dating several months later, split briefly in May 2012, and got back together the following month.
Since their rough patch in 2012, the stars have been more in love than ever. In a recent interview, Gaga admitted that she would marry Kinney if he proposed.
"He is the right guy. How do we know? It's this feeling..." she said.
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